projects / unix-history / blame
| Commit | Line | Data |
|---|---|---|
| 909074c3 SL |
1 | /* @(#)sinh.c 4.1 %G% */ |
| 2 | ||
| 3 | /* | |
| 4 | sinh(arg) returns the hyperbolic sine of its floating- | |
| 5 | point argument. | |
| 6 | ||
| 7 | The exponential function is called for arguments | |
| 8 | greater in magnitude than 0.5. | |
| 9 | ||
| 10 | A series is used for arguments smaller in magnitude than 0.5. | |
| 11 | The coefficients are #2029 from Hart & Cheney. (20.36D) | |
| 12 | ||
| 13 | cosh(arg) is computed from the exponential function for | |
| 14 | all arguments. | |
| 15 | */ | |
| 16 | ||
| 17 | double exp(); | |
| 18 | ||
| 19 | static double p0 = -0.6307673640497716991184787251e+6; | |
| 20 | static double p1 = -0.8991272022039509355398013511e+5; | |
| 21 | static double p2 = -0.2894211355989563807284660366e+4; | |
| 22 | static double p3 = -0.2630563213397497062819489e+2; | |
| 23 | static double q0 = -0.6307673640497716991212077277e+6; | |
| 24 | static double q1 = 0.1521517378790019070696485176e+5; | |
| 25 | static double q2 = -0.173678953558233699533450911e+3; | |
| 26 | ||
| 27 | double | |
| 28 | sinh(arg) | |
| 29 | double arg; | |
| 30 | { | |
| 31 | double temp, argsq; | |
| 32 | register sign; | |
| 33 | ||
| 34 | sign = 1; | |
| 35 | if(arg < 0) { | |
| 36 | arg = - arg; | |
| 37 | sign = -1; | |
| 38 | } | |
| 39 | ||
| 40 | if(arg > 21.) { | |
| 41 | temp = exp(arg)/2; | |
| 42 | if (sign>0) | |
| 43 | return(temp); | |
| 44 | else | |
| 45 | return(-temp); | |
| 46 | } | |
| 47 | ||
| 48 | if(arg > 0.5) { | |
| 49 | return(sign*(exp(arg) - exp(-arg))/2); | |
| 50 | } | |
| 51 | ||
| 52 | argsq = arg*arg; | |
| 53 | temp = (((p3*argsq+p2)*argsq+p1)*argsq+p0)*arg; | |
| 54 | temp /= (((argsq+q2)*argsq+q1)*argsq+q0); | |
| 55 | return(sign*temp); | |
| 56 | } | |
| 57 | ||
| 58 | double | |
| 59 | cosh(arg) | |
| 60 | double arg; | |
| 61 | { | |
| 62 | if(arg < 0) | |
| 63 | arg = - arg; | |
| 64 | if(arg > 21.) { | |
| 65 | return(exp(arg)/2); | |
| 66 | } | |
| 67 | ||
| 68 | return((exp(arg) + exp(-arg))/2); | |
| 69 | } |